1. Field of the Invention and Related Art Statement
This invention relates to an endoscope using, in the image forming optical system, a plurality of liquid crystals having different response frequencies of molecule orientation for a driving signal.
Recently, it is suggested to reduce mechanical moving parts by incorporating liquid crystal devices such as liquid crystal irises and liquid crystal lenses in an image forming optical system or the like for an endoscope.
In the case of incorporating a plurality of liquid crystal devices, there have been problems that it is uneconomical to provide a driving power source for each individual liquid crystal device and therefore a single Power source is preferable but, on the other hand, it is necessary to separately control the individual liquid crystal devices and therefore the power source lines are so many as to be complicated.
Therefore, it has been considered to have a part of the power source lines common.
FIG. 1 shows an example wherein the reference numerals 1, 2 and 3 represent respectively a liquid crystal lens, liquid crystal iris and lens group arranged within the tip part of an endoscope (not illustrated) and forming an objective optical system and the reference symbols P, VR, SW1 and SW2 represent respectively a driving power source, variable resistance, liquid crystal lens switch and liquid crystal iris switch arranged in a hand base operating part (not illustrated). The liquid crystal lens 1 is connected with the resistance VR switch SW.sub.1 and power source p through power source lines l.sub.1 and l.sub.2 and the liquid crystal iris 2 is connected with the switch SW2 and power source P through the power source lines l.sub.2 and l.sub.3. Thus, the power source line l.sub.2 is used as a common line.
For the above mentioned formation, if the number of liquid crystal devices incorporated in the tip part of endoscope increases, the number of the common lines will also increase. This is very insufficient for an endoscope in which the insertable part, through which the power source lines are to be passed, and particularly insufficient for the flexible intermediate part since the parts are desired to be as small as possible in diameter.